Rough vertex curve transform into even curve?
What username:cegaton shows is part 2 of how this issue can be dealt with.(this may be helpful for adjusting the curve before extrusion)

The folowwing image shows a Curve before Alt+c was used to convert the curve to a mesh object.


To adjust a mesh's curvature, you can use proportional editing.  There are several math function options available for doing this and they are shown using the popup dialogue.  The default setting often works well.  Proportional Editing can either be activated using the o key or by clicking the icon shown in the following image.



The Proportional Editing tool has a fallof radius that is shown on the screen as a white circle that can be re-sized either useing the Page_UP, Page_Down or the mouse wheel as shown in the following animating .gif that was made with a program named LICEcap 



Now I would do what cegaton has shown in the answer posted previous to this one.